The use of forming tools to generate various surface configurations in rotating workpieces has generally been known for many years. One conventional type of forming tool uses a cutting insert having a cutting edge which is formed in a prespecified configuration. The insert is forced against an object that is moving at a high speed relative to the cutting tool in order to generate a complementary surface configuration in the workpiece. The forming tool of this type is generally mounted in a movable tool holding assembly so that the tool is movable toward and away from a rotating workpiece along an axis that is substantially perpendicular to the rotating axis of the workpiece. The use of indexable and replaceable inserts in the form tool increases the life of the tool itself and also reduces the overall expense of using the tool. Instead of periodically replacing the tool in its entirety, the insert is simply indexed or replaced. This reduces both maintenance costs and down time since the tool need not be removed or resharpened.
An important element for this type of cutting tool is the arrangement for mounting and retaining the cutting insert on the tool. When using an indexable insert tool, the system or structure for mounting and retaining the indexable insert must accommodate the indexability feature. The cutting insert is placed under extreme forces during a machining operation, and it must be securely fastened to the cutting tool so that the insert will not move relative to its holder. Yet, the insert must be easy to remove from the tool for indexing or replacing, and the mounting system should operate to minimize the chance that the insert will be mispositioned on the tool when the insert is indexed or replaced. The mounting system for the insert must resist wear caused by flying material, e.g. metal, that is cut from the object being machined, and it should be relatively inexpensive to manufacture.
When using a pattern type forming tool, precise and secure positioning is particularly important. The pattern type forming tool is secured to a machine, such as a screw machine or a CNC turning center, and the machine is adjusted once in order for the pattern to be cut into the object in a desired position. Thereafter, the machine need not be readjusted, but the insert must remain in its proper position within tolerances. The machining process places changing forces on the insert depending on the pattern of the insert. For example, the left side of the insert may first engage the object being machined; then, as the machining operation continues, the right side may engage sometime thereafter, so that the force distribution and torque in the cutting insert are abruptly changing. In this type of process, the positioning and securing system for the cutting insert must be able to withstand abrupt changes in stress while reliably maintaining the insert in its proper position.
The cutting tool of the present invention solves the foregoing problems by providing a mounting and retaining system that creates a secure lock between the cutting insert and the cutting tool. The mounting and retaining system is easy and inexpensive to manufacture and the insert is easy to either index or replace.